Eradicating Common Populations of Invasive Species Involves Balancing Efficiency and Fairness

Simple SummaryThe introduction of alien species is one of the major causes of biodiversity loss. The American bullfrog (Lithobates catesbeianus) is considered to be one of the most harmful invasive species which overall threatens native amphibians. The detection of an invasive species in the first stage of its arrival is critical to control its colonization and to avoid its establishment. This early detection requires tools with high sensitivity. Methods based on the analysis of free environmental DNA (eDNA) are promising. The present article develops an eDNA assay to monitor the early process of invasion of the American bullfrog in the Ebre Delta (Spain), in a scenario where the presence of bullfrog specimens is really low and scarcely detected by traditional methods. In 2018, the first bullfrog tadpoles were found for the first time in the Ebre Delta. Two years after, despite the species not being well established, our eDNA assay detected the presence of bullfrogs in several locations. This methodology proved to yield a higher sensitivity with a lower sampling effort than traditional methods. Based on our experience, we also provided solutions to face challenges associated with the use of eDNA. Developing a rapid and low-cost-effective protocol to use in the early stages of an invasion (as occurred with the American bullfrog in the Iberian Peninsula) is essential to facilitate the detection, control, and eradication of an invasive species in the early stages of the invasion process.The American bullfrog (Lithobates catesbeianus) is considered to be one of the most harmful invasive species. In the Iberian Peninsula, this species had been cited occasionally until the year 2018, when L. catesbeianus appeared in the Ebre Delta, and, for the first time, it started breeding in a territory of the Peninsula. Using environmental DNA (eDNA) analysis and visual surveys, the American bullfrog invasion in the Ebre Delta was monitored across two consecutive years (2019–2020). No specimens were observed in 2019, and results for the eDNA survey also failed to detect this species in the Delta. In 2020, two individuals were captured and, under the most conservative criteria to constrain the number of positive detections, eDNA analyses detected the presence of the American bullfrog in at least five locations. Performing an eDNA assay yielded a higher sensitivity with a lower sampling effort than traditional methods. Although the American bullfrog does not appear to still be well-established in the Ebre Delta, only a few bullfrog individuals could be enough for their establishment in suitable habitats. In this context, eDNA assays are essential tools to facilitate the detection, control, and eradication of this species in the first stage of the invasion process.

AimWe test (1) whether invasive angiosperm (flowering plant) species are a phylogenetically clustered subset of all naturalized angiosperm species within an angiosperm assemblage, (2) whether more harmful invasive species are more strongly, or less strongly, related to each other, (3) whether the result of the first test is consistent with those for geographic regions distributed in substantially different climatic conditions, and (4) whether patterns of phylogenetic relatedness for invasive species in regions across climatic gradients are consistent with those for overall naturalized species.LocationChina.Time periodCurrent.TaxonAngiosperms (flowering plants).MethodsWe recognized 28 province‐level regions in China and collated naturalized and invasive species lists of angiosperms for each region. Two phylogenetic metrics (i.e., net relatedness index and nearest taxon index), which represent different depths of evolutionary history, were used to quantify phylogenetic relatedness of angiosperms in China and in each region. Values of the metrics of phylogenetic relatedness were related to temperature and precipitation.ResultsAt the national scale, invasive assemblage is a phylogenetically clustered subset of the naturalized species pool. More harmful invasive species are more strongly clustered. At the regional scale, both naturalized and invasive species are phylogenetically clustered subsets of the national naturalized species pool. Furthermore, invasive species in regional floras are also phylogenetically clustered subsets of their respective regional naturalized species pools.Main conclusionsInvasive angiosperm species are a phylogenetically clustered subset of naturalized angiosperm species. More harmful invasive species are more strongly clustered with respect to their naturalized species pools, compared to less harmful invasive species. Our findings have significant implications to predicting and controlling invasive species based on phylogenetic relatedness among naturalized species.

Ecological impact of phytoinvasions in Ukraine

Eradication of invasive alien species supports the recovery of native biodiversity. A new European Union Regulation introduces obligations to eradicate the most harmful invasive species. However, eradications of charismatic mammals may encounter strong opposition. Considering the case study of the eastern grey squirrel (Sciurus carolinensis Gmelin, 1788) in central Italy, we developed a structured decision-making technique based on a Bayesian decision network model and explicitly considering the plurality of environmental values of invasive species management to reduce potential social conflicts. The model identified priority areas for management activities. These areas corresponded to the core of the grey squirrel range, but they also included peripheral zones, where rapid eradication is fundamental to prevent the spread of squirrels. However, when the model was expanded to integrate the attitude of citizens towards the project, the intervention strategy slightly changed. In some areas, the citizens' support was limited, and this resulted in a reduced overall utility of intervention. The suggested approach extends the scientific basis for management decisions, evaluated in terms of technical efficiency, feasibility and social impact. Here, the Bayesian decision network model analysed the potential technical and social consequences of management actions, and it responded to the need for transparency in the decision-making process, but it can easily be extended to consider further issues that are common in many mammal eradication programmes. Owing to its flexibility and comprehensiveness, it provides an innovative example of how to plan rapid eradication or control activities, as required by the new EU Regulation. © 2016 Society of Chemical Industry.

Botany is the root and the future of invasion biology.

Socotra Island has significant ecological and economic importance at local, national and global scales. Invasive plant species are often considered as potential competitors of native species due to their usual greater capacity for colonization and expansion. The spread of alien plant species has long been recognized as one of the most significant environmental changes due to its ability to decrease biodiversity and alter ecosystem processes. In areas with homogeneity population of wild invasive species especially Argemone mexicana, 32 random sites were randomly detected. Ninety six Quadrates plots were laid down to study the interaction between the invasive plant and the native species especially with conservation attention of endemic plant species. The main aims is to provide base informatics data to establish comprehensive habitat surveillance programs to enable early detection and rapid response of IAS, prevent both intentional or accidental introductions of harmful invasive alien species to the Socotra Island and reduce the likelihood of alien species invasions by decreasing stresses on vulnerable at-risk ecosystems and species. This study was conducted to identify the different types of invasive species present, the rate and pattern of invasion, its intensity, association of invaders and their habitat preference in the Socotra ecosystem. Vegetation sampled in 96 quadrats, each 10 m _ 10 m; through a combination of random and systematic sampling recorded 42 plant species of 36 genera belonging to 24 families with around 10% was recorded as invasive species. Diversity indices like richness, evenness, Simpson and Shannon-Wiener have been analyzed.

Analysis of numbers of invasive species (insects, plants, plant diseases) in each of Chinese provinces and the world’s climatic zones respectively, demonstrated positive correlations between diversity of bioinvasion and air temperature and precipitation (the two main criteria for classifying world climate types). When the air temperature is within the range of 1–25°C, the degree of diversity of invasive alien species increases exponentially with air temperature. However, when the air temperature falls outside the range of 1–25°C, the diversity of harmful invasive alien species changes with air temperature in a parabolic pattern, showing a “mid-latitude bulge”. Namely, when air temperatures are too high or too low, a lower average invasion frequency of harmful alien species is observed. Invasion by harmful invasive alien species is more weakly related to precipitation. Different climatic zones showed dramatic differences in resistance to the invasion of invasive alien species due to their different characteristic climatic factors, mainly including air temperature and precipitation.

Forecasting habitat suitability and connectivity can be central to both controlling range expansion of invasive species and promoting native species conservation, especially under changing climate conditions. This study aimed to identify and prioritize areas in Spain to control the expansion of one of the most harmful invasive species in Europe, the American mink, while conserving its counterpart, the endangered European mink, under current and future conditions. We used ensemble habitat suitability and dynamic connectivity models to predict species ranges and movement routes considering likely climate change under three emission scenarios. Then, using habitat availability metrics, we prioritized areas for invasive mink control and native mink conservation and classified them into different management zones that reflected the overlap between species and threat from American to European minks. Results suggest that both species are likely to experience declines in habitat and connectivity under climate change scenarios with significantly larger declines by the end of the century for European minks (72 and 80% respectively) than for American minks (41 and 32%). Priority areas for management of both species varied over time and across emission scenarios, with a general shift in priority habitat towards the North-East of the study area. Our findings demonstrate how habitat suitability and dynamic connectivity approaches can guide long-term management strategies to control invasive species and conserve native species while accounting for likely landscape changes. The simultaneous study of both invasive and native species can support prioritized management action and inform management planning of the intensity, extent, and techniques of intervention depending on the overlap between species.

Pink muhly grass (Muhlenbergia capillaris Trin.) is an exotic species in South Korea and is popular worldwide as an ornamental grass for landscaping purposes. The Ministry of Environment in South Korea has categorized this species as an “Ecosystem Hazard Class 2” plant, requiring long‐term monitoring to assess its ecological impacts on native species and communities. In this study, a 2‐year greenhouse experiment was conducted using M. capillaris and 17 native plant species (6 annuals, 8 nonwoody perennials, and 3 woody perennials) to test the hypothesis that if M. capillaris is an invasive species, it will negatively affect the establishment and growth of native plants in competitive pairings compared with controls (native species grown in monoculture). Results showed that the mean canopy cover of native plants in competition with M. capillaris was not significantly different from monocultures of the corresponding native species. There were also no significant differences in mean aboveground biomass production between native species growing with M. capillaris compared to corresponding native monocultures. Results indicate that M. capillaris did not significantly affect the establishment and growth of the 17 native species investigated. The minimal impacts suggest that M. capillaris may not be a harmful invasive species, but further monitoring of its spread will be required to test these findings under natural conditions.

ABSTRACTDetailed knowledge of patterns of native species richness, an important component of biodiversity, and non‐native species invasions is often lacking even though this knowledge is essential to conservation efforts. However, we cannot afford to wait for complete information on the distribution and abundance of native and harmful invasive species. Using information from counties well surveyed for plants across the USA, we developed models to fill data gaps in poorly surveyed areas by estimating the density (number of species km−2) of native and non‐native plant species. Here, we show that native plant species density is non‐random, predictable, and is the best predictor of non‐native plant species density. We found that eastern agricultural sites and coastal areas are among the most invaded in terms of non‐native plant species densities, and that the central USA appears to have the greatest ratio of non‐native to native species. These large‐scale models could also be applied to smaller spatial scales or other taxa to set priorities for conservation and invasion mitigation, prevention, and control efforts.

Tiopurinas y riesgo de linfoma en la enfermedad inflamatoria intestinal

A global organism detection and monitoring system for non-native species

Numerous invasive aquatic species introductions can be traced to the aquarium trade. Many potentially harmful aquarium species may be difficult to identify based on morphology alone. As such, some prohibited or invasive species may be available for purchase if they are mislabeled as species without restrictions. Here we compare molecular identifications to internet vendors’ identifications for accessions of a popular genus of aquarium plants that are difficult to distinguish morphologically (Myriophyllum; watermilfoils). Specifically, we identified the extensive mislabeling of M. heterophyllum—an invasive species in the northeastern and western US. Furthermore, genotypes of M. heterophyllum found in our aquarium survey have also been found in invasive populations, suggesting their potential introduction through escape from aquaria, water gardens, or nurseries. Two additional taxa were sold under incorrect names. Finally, our survey revealed that Myriophyllum taxa present in the aquarium trade generally have poorly known distributions and ecologies, and therefore their invasive potential is unknown. Our study confirms that molecular identification methods can provide a valuable tool to survey commercial pathways for potentially harmful species that are otherwise difficult to identify.

Summary1.To ensure the successful detection, control and eradication of invasive plant species, we need information that can identify areas prone to invasions and criteria that can point out which particular populations may become foci of further spread. Specifically, our work aimed to develop statistical models that identify hotspots of invasive plant species and evaluate the conditions that give rise to successful populations of invasive species.2.We combined extensive data sets on invasive species richness and on species per cent ground cover, together with climate, local habitat and land cover data. We then estimated invasive species richness as a function of those environmental variables by developing a spatially explicit generalized linear model within a hierarchical Bayesian framework. In a second analysis, we used an ordinal logistic regression model to quantify invasive species abundance as a function of the same set of predictor variables.3.Our results show which locations in the studied region, north‐eastern USA, are prone to plant species invasions given the combination of climatic and land cover conditions particular to the sites. Predictions were also generated under a range of climate scenarios forecasted for the region, which pointed out at an increase in invasive species incidence under the most moderate forecast. Predicted abundance for some of the most common invasive plant species,Berberis thumbergii,Celastrus orbiculatus,Euonymus alata,Elaeagnus umbellataandRosa multiflora, allowed us to identify the specific conditions that promote successful population growth of these species, populations that could become foci of further spread.4.Synthesis and applications.Reliable predictions of plants’ invasive potential are crucial for the successful implementation of control and eradication management plans. By following a multivariate approach the parameters estimated in this study can now be used on targeted locations to evaluate the risk of invasions given the local climate and landscape structure; they can also be applied under different climate scenarios and changing landscapes providing an array of possible outcomes. In addition, this modelling approach can be easily used in other regions and for other species.

QuestionsThe impact of invasive species on community structure and function varies, yet it is difficult to predict. Different hypotheses have been proposed to predict invasive species establishment and impact on resident communities, based on characteristics of the resident community and/or environmental conditions. Invasive species, however, interact with both native and exotic species. The interaction with exotic species is important, as it can result in secondary invasion or greater impact on native species. Smooth brome (Bromus inermis Leyss.) is a widely planted forage crop, but also a harmful invasive species in North American grasslands, yet little is known about the variability of its impact on resident communities. We ask (1) whether smooth brome has a consistent impact on community structure and function; (2) which biotic and abiotic conditions are associated with smooth brome's impact on resident communities; and (3) whether smooth brome has a similar impact on native and exotic species, and which biotic or abiotic conditions drive the interaction of smooth brome with native and exotic species.LocationEight grasslands throughout Alberta, Canada.MethodsWe used space‐for‐time substitutions to quantify smooth brome's impact on different aspects of community structure and function, and whether it varies depending on species richness, productivity, temperature, precipitation and variation in precipitation.ResultsSmooth brome had a consistent negative impact on community structure and function. However, the strength of the effect depended on aspects of the local community. Smooth brome impacts on species richness were higher in species‐rich areas, while impact on resident species biomass was larger in productive, warmer and more variable sites. In most sites the negative effect of smooth brome on species richness was higher for native species, compared to exotics. Impact on native and exotic species richness was larger in species‐rich and more variable sites, respectively.ConclusionsUnderstanding and predicting smooth brome's impact on community structure and function can help managers prescribe management plans to reduce negative impacts of smooth brome on native communities. Predicting the interaction of smooth brome with exotic species may be just as important when planning management strategies, to avoid secondary invasion and/or the accumulation of exotic species.